Organometallic compound, organic light-emitting device including the same, and electronic apparatus including the organic light-emitting device

ABSTRACT

An organometallic compound represented by Formula 1:wherein, M is a transition metal, X11 is N or C(R11), X12 is N or C(R12), at least one of X11 and X12 is N, ring CY2, ring CY31, ring CY32, and ring CY4 are each independently a C3-C60 carbocyclic group or a C1-C60 heterocyclic group, Y2 to Y4 are each independently C or N, A2 to A4 are each independently a chemical bond, O, or S, a1 to a3 are each independently an integer from 1 to 3, and the remaining substitutions are as provided in the detailed description.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority to Korean Patent Application No. 10-2022-0080854, filed on Jun. 30, 2022, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

The subject matter relates to an organometallic compound, an organic light-emitting device including the same, and an electronic apparatus including the organic light-emitting device.

2. Description of the Related Art

Organic light-emitting devices (OLEDs) are self-emissive devices, which have improved characteristics in terms of viewing angles, response time, luminance, driving voltage, and response speed. In addition, OLEDS can produce full-color images.

In a typical example, an organic light-emitting device may include an anode, a cathode, and an organic layer arranged between the anode and the cathode, wherein the organic layer includes an emission layer. A hole transport region may be arranged between the anode and the emission layer, and an electron transport region may be arranged between the emission layer and the cathode. Holes provided from the anode may move toward the emission layer through the hole transport region, and electrons provided from the cathode may move toward the emission layer through the electron transport region. The holes and the electrons recombine in the emission layer to produce excitons. These excitons may transition from an excited state to a ground state, thereby generating light.

SUMMARY

Provided are an organometallic compound, an organic light-emitting device including the same, and an electronic apparatus including the organic light-emitting device.

According to an aspect, provided is an organometallic compound represented by Formula 1:

wherein, in Formula 1,

-   -   M is a transition metal,     -   X₁₁ is N or C(R₁₁),     -   X₁₂ is N or C(R₁₂),     -   at least one of X₁₁ and X₁₂ is N,     -   ring CY₂, ring CY₃₁, ring CY₃₂, and ring CY₄ are each         independently a C₃-C₆₀ carbocyclic group or a C₁-C₆₀         heterocyclic group,     -   Y₂ to Y₄ are each independently C or N,     -   A₂ to A₄ are each independently a chemical bond, O, or S,     -   T₁ may be a single bond, a double bond,         *—N[(L₁)_(b1)-(R_(1a))]—*′, *—B(R_(1a))—*′, *—P(R_(1a))—*′,         *—C(R_(1a))(R_(1b))—*′, *—Si(R_(1a))(R_(1b))—*′,         *—Ge(R_(1a))(R_(1b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′,         *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(1a))═*′, *═C(R_(1a))—*′,         *—C(R_(1a))═C(R_(1b))—*′, *—C(═S)—*′, or *—C≡C—*′,     -   T₂ may be a single bond, a double bond,         *—N[(L₂)_(b2)-(R_(2a))]—*′, *—B(R_(2a))—*′, *—P(R_(2a))—*′,         *—C(R_(2a))(R_(2b))—*′, *—Si(R_(2a))(R_(2b))—*′,         *—Ge(R_(2a))(R_(2b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′,         *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(2a))═*′, *═C(R_(2a))—*′,         *—C(R_(2a))═C(R_(2b))—*′, *—C(═S)—*′, or *—C≡C—*′,     -   T₃ may be a single bond, a double bond,         *—N[(L₃)_(b3)-(R_(3a))]—*′, *—B(R_(3a))—*′, *—P(R_(3a))—*′,         *—C(R_(3a))(R_(3b))—*′, *—Si(R_(3a))(R_(3b))—*′,         *—Ge(R_(3a))(R_(3b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′,         *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(3a))═*′, *═C(R_(3a))—*′,         *—C(R_(3a))═C(R_(3b))—*′, *—C(═S)—*′, or *—C≡C—*′,     -   a1 to a3 are each independently an integer from 1 to 3,     -   * and *′ each indicate a binding site to a neighboring atom,     -   L₁ to L₃ are each independently a single bond, a C₅-C₃₀         carbocyclic group unsubstituted or substituted with at least one         R_(10a), or a C₁-C₃₀ heterocyclic group unsubstituted or         substituted with at least one R_(10a),     -   b1 to b3 are each independently an integer from 1 to 3, R_(1a),         R_(1b), R₂, R_(2a), R_(2b), R_(3a), R_(3b), R₄, R_(10a), R₁₁ to         R₁₃, R₃₁, and R₃₂ are each independently hydrogen, deuterium,         —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro         group, an amino group, an amidino group, a hydrazine group, a         hydrazone group, a carboxylic acid group or a salt thereof, a         sulfonic acid group or a salt thereof, a phosphoric acid group         or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl         group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a         substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted         or unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₁-C₆₀ alkylthio group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₂-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₇-C₆₀ alkyl aryl group, a substituted or unsubstituted C₇-C₆₀         aryl alkyl group, a substituted or unsubstituted C₆-C₆₀ aryloxy         group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a         substituted or unsubstituted C₁-C₆₀ heteroaryl group, a         substituted or unsubstituted C₂-C₆₀ alkyl heteroaryl group, a         substituted or unsubstituted C₂-C₆₀ heteroaryl alkyl group, a         substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a         substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a         substituted or unsubstituted monovalent non-aromatic condensed         polycyclic group, a substituted or unsubstituted monovalent         non-aromatic condensed heteropolycyclic group, —Si(Q₁)(Q₂)(Q₃),         —Ge(Q₁)(Q₂)(Q₃), —N(Q₄)(Q₅), —B(Q₆)(Q₇), —P(Q₈)(Q₉), or         —P(═O)(Q₈)(Q₉),     -   d2, d31, d32, and d4 are each independently an integer from 0 to         10,     -   at least one substituent of the substituted C₅-C₃₀ carbocyclic         group, the substituted C₁-C₃₀ heterocyclic group, the         substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl         group, the substituted C₂-C₆₀ alkynyl group, the substituted         C₁-C₆₀ alkoxy group, the substituted C₁-C₆₀ alkylthio group, the         substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀         heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl         group, the substituted C₁-C₁₀ heterocycloalkenyl group, the         substituted C₆-C₆₀ aryl group, the substituted C₇-C₆₀ alkyl aryl         group, the substituted C₇-C₆₀ aryl alkyl group, the substituted         C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the         substituted C₁-C₆₀ heteroaryl group, the substituted C₂-C₆₀         alkyl heteroaryl group, the substituted C₂-C₆₀ heteroaryl alkyl         group, the substituted C₁-C₆₀ heteroaryloxy group, the         substituted C₁-C₆₀ heteroarylthio group, the substituted         monovalent non-aromatic condensed polycyclic group, and the         substituted monovalent non-aromatic condensed heteropolycyclic         group is:     -   deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃,         —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, or a C₁-C₆₀ alkylthio         group,     -   a C₁-C₆ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, a C₁-C₆₀alkoxy group, or a C₁-C₆₀ alkylthio group, each         substituted with at least one of deuterium, —F, —Cl, —Br, —I,         —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group,         a cyano group, a nitro group, an amino group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl         group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl         group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a         C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl         heteroaryl group, a C₂-C₆₀ heteroaryl alkyl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group,         —Si(Q₁₁)(Q₁₂)(Q₁₃), —Ge(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₄)(Q₁₅),         —B(Q₁₆)(Q₁₇), —P(Q₁₈)(Q₁₉), —P(═O)(Q₁₈)(Q₁₉), or a combination         thereof,     -   a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₂-C₆₀ alkyl heteroaryl group, a C₂-C₆₀ heteroaryl alkyl group,         a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         monovalent non-aromatic condensed polycyclic group, or a         monovalent non-aromatic condensed heteropolycyclic group,     -   a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₂-C₆₀ alkyl heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, or a monovalent non-aromatic         condensed heteropolycyclic group, each substituted with at least         one of deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂,         —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro         group, an amino group, an amidino group, a hydrazine group, a         hydrazone group, a carboxylic acid group or a salt thereof, a         sulfonic acid group or a salt thereof, a phosphoric acid group         or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group,         a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₁-C₆₀         alkylthio group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀         heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀         heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl         aryl group, a C₇-C₆₀ aryl alkyl group, a C₆-C₆₀ aryloxy group, a         C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl         heteroaryl group, a C₂-C₆₀ heteroaryl alkyl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group,         —Si(Q₂₁)(Q₂₂)(Q₂₃), —Ge(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₄)(Q₂₅),         —B(Q₂₆)(Q₂₇), —P(Q₂₈)(Q₂₉), —P(═O)(Q₂₈)(Q₂₉), or a combination         thereof, or     -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —Ge(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₄)(Q₃₅),         —B(Q₃₆)(Q₃₇), —P(Q₃₈)(Q₃₉), or —P(═O)(Q₃₈)(Q₃₉), and     -   Q₁ to Q, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ are each         independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, a         hydroxyl group, a cyano group, a nitro group, an amino group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₁-C₆₀ alkylthio group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₇-C₆₀ alkyl aryl group, a substituted or unsubstituted C₇-C₆₀         aryl alkyl group, a substituted or unsubstituted C₆-C₆₀ aryloxy         group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a         substituted or unsubstituted C₁-C₆₀ heteroaryl group, a         substituted or unsubstituted C₂-C₆₀ alkyl heteroaryl group, a         substituted or unsubstituted C₂-C₆₀ heteroaryl alkyl group, a         substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a         substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a         substituted or unsubstituted monovalent non-aromatic condensed         polycyclic group, or a substituted or unsubstituted monovalent         non-aromatic condensed heteropolycyclic group.

According to another aspect, an organic light-emitting device includes a first electrode, a second electrode, and an organic layer arranged between the first electrode and the second electrode, wherein the organic layer includes an emission layer, and wherein the organic layer further includes at least one of the organometallic compound.

According to still another aspect, an electronic apparatus includes the organic light-emitting device.

Additional aspects will be set forth in part in the detailed description that follows and, in part, will be apparent from the detailed description, or may be learned by practice of the presented exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an organic light-emitting device according to one or more embodiments;

FIG. 2 is a graph of normalized intensity (arbitrary units, a.u.) versus wavelength (nanometers, nm) and shows photoluminescence (PL) spectra of compounds according to one or more exemplary embodiments and comparative compounds;

FIG. 3 is a graph of normalized intensity (a.u.) versus wavelength (nm) and shows electroluminescence (EL) spectra of light-emitting devices respectively including compounds according to one or more exemplary embodiments and comparative compounds; and

FIG. 4 is a graph of luminance (candela per square meter, cd/m²) versus voltage (Volts, V) and shows luminance of compounds according to one or more exemplary embodiments and comparative compounds according to voltages.

DETAILED DESCRIPTION

Reference will now be made in further detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present exemplary embodiments may have different forms and should not be construed as being limited to the detailed descriptions set forth herein. Accordingly, the exemplary embodiments are merely described in further detail below, and by referring to the figures, to explain particular aspects and features. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

The terminology used herein is for the purpose of describing one or more exemplary embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “or” means “and/or.” It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the present embodiments.

Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.

It will be understood that when an element is referred to as being “on” another element, it can be directly in contact with the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this general inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Hereinafter, a work function or a highest occupied molecular orbital (HOMO) energy level is expressed as an absolute value from a vacuum level. In addition, when the work function or the HOMO energy level is referred to be “deep,” “high” or “large,” the work function or the HOMO energy level has a large absolute value based on “0 eV” of the vacuum level, while when the work function or the HOMO energy level is referred to be “shallow,” “low,” or “small,” the work function or HOMO energy level has a small absolute value based on “0 eV” of the vacuum level.

An aspect provides an organometallic compound represented by Formula 1:

wherein, in Formula 1,

-   -   M is a transition metal.

In one or more embodiments, M in Formula 1 may be a first-row transition metal of the Periodic Table of Elements, a second-row transition metal of the Periodic Table of Elements, or a third-row transition metal of the Periodic Table of Elements.

For example, M in Formula 1 may be iridium (Ir), platinum (Pt), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), thulium (Tm), rhodium (Rh), palladium (Pd), or gold (Au).

In one or more embodiments, M in Formula 1 may be platinum, palladium, or gold.

For example, M in Formula 1 may be platinum.

In Formula 1,

-   -   X₁₁ is N or C(R₁₁),     -   X₁₂ is N or C(R₁₂), and     -   at least one of X₁₁ and X₁₂ is N.

In one or more embodiments, i) X₁₁ may be N, and X₁₂ may be C(R₁₂);

-   -   ii) X₁₁ may be C(R₁₁), and X₁₂ may be N; or     -   iii) X₁₁ may be N, and X₁₂ may be N, and     -   R₁₁ and R₁₂ are each as described herein.

In Formula 1, ring CY₂, ring CY₃₁, ring CY₃₂, and ring CY₄ are each independently a C₃-C₆₀ carbocyclic group or a C₁-C₆₀ heterocyclic group.

In one or more embodiments, ring CY₂, ring CY₃₁, ring CY₃₂, and ring CY₄ may each independently be a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a thiophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluoren-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluoren-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzotriazole, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group.

Y₂ to Y₄ are each independently C or N.

In one or more embodiments, at least one of Y₂ to Y₄ may be N.

In one or more embodiments, Y₂ may be C, Y₃ may be C, and Y₄ may be N;

-   -   Y₂ may be N, Y₃ may be C, and Y₄ may be C;     -   Y₂ may be C, Y₃ may be N, and Y₄ may be C;     -   Y₂ may be N, Y₃ may be C, and Y₄ may be N;     -   Y₂ may be N, Y₃ may be N, and Y₄ may be C;     -   Y₂ may be C, Y₃ may be N, and Y₄ may be N; or     -   Y₂ may be N, Y₃ may be N, and Y₄ may be N.

A₂ to A₄ are each independently a chemical bond, O, or S.

The chemical bond may be a covalent bond, a metal bond, or a coordinate bond, but embodiments are not limited thereto.

T₁ may be a single bond, a double bond, *—N[(L₁)_(b1)-(R_(1a))]—*′, *—B(R_(1a))—*′, *—P(R_(1a))—*′, *—C(R_(1a))(R_(1b))—*′, *—Si(R_(1a))(R_(1b))—*′, *—Ge(R_(1a))(R_(1b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(1a))═*′, *═C(R_(1a))—*′, *—C(R_(1a))═C(R_(1b))—*′, *—C(═S)—*′, or *—C≡C—*′.

T₂ may be a single bond, a double bond, *—N[(L₂)_(b2)-(R_(2a))]—*′, *—B(R_(2a))—*′, *—P(R_(2a))—*′, *—C(R_(2a))(R_(2b))—*′, *—Si(R_(2a))(R_(2b))—*′, *—Ge(R_(2a))(R_(2b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—, S(═O)—*′, *—S(═O)₂—*′, *—C(R_(2a))═*′, *═C(R_(2a))—*′, *—C(R_(2a))═C(R_(2b))—*′, *—C(═S)—*′, or *—C≡C—*′.

T₃ may be a single bond, a double bond, *—N[(L₃)_(b3)-(R_(3a))]—*′, *—B(R_(3a))—*′, *—P(R_(3a))—*′, *—C(R_(3a))(R_(3b))—*′, *—Si(R_(3a))(R_(3b))—*′, *—Ge(R_(3a))(R_(3b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(3a))═*′, *═C(R_(3a))—*′, *—C(R_(3a))═C(R_(3b))—*′, *—C(═S)—*′, or *—C≡C—*′.

a1 to a3 in Formula 1 respectively indicate the number of T₁(s) to the number of T₃(s) and may each independently be an integer from 1 to 3 (for example, 1, 2, or 3).

a1 to a3 are each independently an integer from 1 to 3.

In one or more embodiments, at least one of T₁ and T₃ may be a single bond.

For example, T₁ may be a single bond; T₃ may be a single bond; or T₁ and T₃ may each be a single bond.

When a1 is 2 or greater, two or more of T₁ may be identical to or different from each other, when a2 is 2 or greater, two or more of T₂ may be identical to or different from each other, and when a3 is 2 or greater, two or more of T₃ may be identical to or different from each other.

In one or more embodiments, T₂ may be *—N[(L₂)_(b2)-(R_(2a))]—*′, *—S—*′, *—Se—*′, or *—O—*′, and a2 may be 1.

In one or more embodiments, T₂ may be *—O—*′ and a2 may be 1.

* and *′ each indicate a binding site to a neighboring atom in the formulae for T₁, T₂, and T₃.

L₁ to L₃ are each independently a single bond, a C₅-C₃₀ carbocyclic group unsubstituted or substituted with at least one R_(10a), or a C₁-C₃₀ heterocyclic group unsubstituted or substituted with at least one R_(10a).

b1 to b3 are each independently an integer from 1 to 3.

R_(1a), R_(1b), R₂, R_(2a), R_(2b), R_(3a), R_(3b), R₄, R_(10a), R₁₁ to R₁₃, R₃₁, and R₃₂ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₁-C₆₀ alkylthio group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₇-C₆₀ alkyl aryl group, a substituted or unsubstituted C₇-C₆₀ aryl alkyl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₂-C₆₀ alkyl heteroaryl group, a substituted or unsubstituted C₂-C₆₀ heteroaryl alkyl group, a substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q₁)(Q₂)(Q₃), —Ge(Q₁)(Q₂)(Q₃), —N(Q₄)(Q₅), —B(Q₆)(Q₇), —P(Q₈)(Q₉), or —P(═O)(Q₈)(Q₉).

d2, d31, d32, and d4 are each independently an integer from 0 to 10.

d2, d31, d32, and d4 in Formula 1 respectively indicate the number of R₂, the number of R₃₁, the number of R₃₂, and the number of R₄, and may each independently be an integer from 0 to 10 (for example, 0, 1, 2, 3, or 4). When d2 is 2 or greater, two or more of R₂ may be identical to or different from each other, when d31 is 2 or greater, two or more of R₃₁ may be identical to or different from each other, when d32 is 2 or greater, two or more of R₃₂ may be identical to or different from each other, and when d4 is 2 or greater, two or more of R₄ may be identical to or different from each other.

At least one substituent of the substituted C₅-C₃₀ carbocyclic group, the substituted C₁-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₁-C₆₀ alkylthio group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₇-C₆₀ alkyl aryl group, the substituted C₇-C₆₀ aryl alkyl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group, the substituted C₂-C₆₀ alkyl heteroaryl group, the substituted C₂-C₆₀ heteroaryl alkyl group, the substituted C₁-C₆₀ heteroaryloxy group, the substituted C₁-C₆₀ heteroarylthio group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group is:

-   -   deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃,         —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, or a C₁-C₆₀ alkylthio         group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, a C₁-C₆₀ alkoxy group, or a C₁-C₆₀ alkylthio group, each         substituted with at least one of deuterium, —F, —Cl, —Br, —I,         —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group,         a cyano group, a nitro group, an amino group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl         group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl         group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a         C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀         heteroarylthio group, a monovalent non-aromatic condensed         polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, —Si(Q₁₁)(Q₁₂)(Q₁₃), —Ge(Q₁₁)(Q₁₂)(Q₁₃),         —N(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), —P(Q₁₈)(Q₁₉), —P(═O)(Q₁₈)(Q₁₉), or a         combination thereof;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroaryloxy group, a         C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed         polycyclic group, or a monovalent non-aromatic condensed         heteropolycyclic group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₂-C₆₀ alkyl heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a         C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed         polycyclic group, or a monovalent non-aromatic condensed         heteropolycyclic group, each substituted with at least one of         deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃,         —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₁-C₆₀ alkylthio group,         a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₇-C₆₀ aryl         alkyl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a         C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a         C₂-C₆₀ heteroaryl alkyl group, a C₁-C₆₀ heteroaryloxy group, a         C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed         polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, —Si(Q₂₁)(Q₂₂)(Q₂₃), —Ge(Q₂₁)(Q₂₂)(Q₂₃),         —N(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), —P(Q₂₈)(Q₂₉), —P(═O)(Q₂₈)(Q₂₉), or a         combination thereof; or     -   —Si(Q₃₁)(Q₃₂)(Q₃₃), —Ge(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₄)(Q₃₅),         —B(Q₃₆)(Q₃₇), —P(Q₃₈)(Q₃₉), or —P(═O)(Q₃₈)(Q₃₉).

Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₁-C₆₀ alkylthio group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₇-C₆₀ alkyl aryl group, a substituted or unsubstituted C₇-C₆₀ aryl alkyl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₂-C₆₀ alkyl heteroaryl group, a substituted or unsubstituted C₂-C₆₀ heteroaryl alkyl group, a substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group.

In one or more embodiments, R_(1a), R_(1b), R_(2a), R_(2b), R_(3a), R_(3b), R₄, R_(10a), R₁₁ to R₁₃, R₂, R₃₁, and R₃₂ may each independently be:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂,         —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro         group, an amino group, an amidino group, a hydrazine group, a         hydrazone group, a carboxylic acid group or a salt thereof, a         sulfonic acid group or a salt thereof, a phosphoric acid group         or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group,         or a C₁-C₂₀ alkylthio group;     -   a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, or a C₁-C₆₀         alkylthio group, each substituted with at least one of         deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃,         —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexyl         group, a cycloheptyl group, a cyclooctyl group, an adamantanyl         group, a norbornanyl group, a norbornenyl group, a cyclopentenyl         group, a cyclohexenyl group, a cycloheptenyl group, a phenyl         group, a naphthyl group, a pyridinyl group, a pyrimidinyl group,         or a combination thereof;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclooctyl group, an adamantanyl group, a norbornanyl group, a         norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,         a cycloheptenyl group, a phenyl group, a naphthyl group, a         fluorenyl group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, an isoindolyl group, an indolyl         group, an indazolyl group, a purinyl group, a quinolinyl group,         an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a cinnolinyl group, a carbazolyl         group, a phenanthrolinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, an imidazopyridinyl group, or an         imidazopyrimidinyl group;     -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclooctyl group, an adamantanyl group, a norbornanyl group, a         norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,         a cycloheptenyl group, a phenyl group, a naphthyl group, a         fluorenyl group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, an isoindolyl group, an indolyl         group, an indazolyl group, a purinyl group, a quinolinyl group,         an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a cinnolinyl group, a carbazolyl         group, a phenanthrolinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, a benzoisothiazolyl         group, a benzoxazolyl group, an isobenzoxazolyl group, a         triazolyl group, a tetrazolyl group, an oxadiazolyl group, a         triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl         group, a benzocarbazolyl group, a dibenzocarbazolyl group, an         imidazopyridinyl group, or an imidazopyrimidinyl group, each         substituted with at least one of deuterium, —F, —Cl, —Br, —I,         —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group,         a cyano group, a nitro group, an amino group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a         C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkylthio group, a cyclopentyl         group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl         group, an adamantanyl group, a norbornanyl group, a norbornenyl         group, a cyclopentenyl group, a cyclohexenyl group, a         cycloheptenyl group, a phenyl group, a naphthyl group, a         fluorenyl group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, an isoindolyl group, an indolyl         group, an indazolyl group, a purinyl group, a quinolinyl group,         an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a cinnolinyl group, a carbazolyl         group, a phenanthrolinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, a benzoisothiazolyl         group, a benzoxazolyl group, an isobenzoxazolyl group, a         triazolyl group, a tetrazolyl group, an oxadiazolyl group, a         triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl         group, a benzocarbazolyl group, a dibenzocarbazolyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group,         —Si(Q₃₁)(Q₃₂)(Q₃₃), or a combination thereof; or     -   —Si(Q₁)(Q₂)(Q₃), —Ge(Q₁)(Q₂)(Q₃), —N(Q₄)(Q₅), —B(Q₆)(Q₇),         —P(Q₈)(Q₉), or —P(═O)(Q₈)(Q₉), and     -   Q₁ to Q₉ and Q₃₁ to Q₃₃ may each independently be:     -   —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂,         —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, or         —CD₂CDH₂;     -   an n-propyl group, an isopropyl group, an n-butyl group, an         isobutyl group, a sec-butyl group, a tert-butyl group, an         n-pentyl group, an isopentyl group, a sec-pentyl group, a         tert-pentyl group, a phenyl group, or a naphthyl group; or     -   an n-propyl group, an isopropyl group, an n-butyl group, an         isobutyl group, a sec-butyl group, a tert-butyl group, an         n-pentyl group, an isopentyl group, a sec-pentyl group, a         tert-pentyl group, a phenyl group, or a naphthyl group, each         substituted with at least one of deuterium, a C₁-C₁₀ alkyl         group, a phenyl group, or a combination thereof.

In one or more embodiments, R_(1a), R_(1b), R_(2a), R_(2b), R_(3a), R_(3b), R₄, R_(10a), R₁₁ to R₁₃, R₂, R₃₁, and R₃₂ may each independently be:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂,         —CF₃, —CF₂H, —CFH₂, a cyano group, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy         group, or a C₁-C₆₀ alkylthio group;     -   a group represented by one of Formulae 9-1 to 9-61, 9-201 to         9-237, 10-1 to 10-129, or 10-201 to 10-355;     -   a group represented by one of Formulae 9-1 to 9-61, 9-201 to         9-237, 10-1 to 10-129, or 10-201 to 10-350 in which at least one         hydrogen is substituted with deuterium, —F, or a cyano group; or     -   —Si(Q₁)(Q₂)(Q₃), —Ge(Q₁)(Q₂)(Q₃), or —N(Q₄)(Q₅), and     -   Q₁ to Q₅ are each as described herein:

wherein, in Formulae 9-1 to 9-61, 9-201 to 9-237, 10-1 to 10-129, and 10-201 to 10-355, * indicates a binding site to a neighboring atom, “Ph” indicates a phenyl group, “TMS” indicates a trimethylsilyl group, and “TMG” indicates a trimethylgermyl group.

In one or more embodiments, a group represented by

in Formula 1 may be a group represented by one of Formulae 2-1 to 2-3:

wherein, in Formulae 2-1 to 2-3,

-   -   Y₂₁ to Y₂₃ may each independently be C or N,     -   Y₂₁ and Y₂ may be linked to each other via a chemical bond, Y₂         and Y₂₁ are linked to each other via a chemical bond, Y₂ and Y₂₂         may be linked to each other via a chemical bond, Y₂ and Y₂₃ are         linked to each other via a chemical bond, and Y₂₂ and Y₂₃ may be         linked to each other via a chemical bond,     -   *′ indicates a binding site to T₁, *″ indicates a binding site         to T₂, and * indicates a binding site to A₂ or M, and     -   ring CY₂, Y₂, R₂, and d2 are each as described herein.

In one or more embodiments, a group represented by

in Formula 1 may be a group represented by one of Formulae CY2-1 to CY2-35:

wherein, in Formulae CY2-1 to CY2-35,

-   -   Y₂ may be C or N,     -   R₂₁ to R₂₉ may each independently be as described in connection         with R₂,     -   * indicates a binding site to M or A₂,     -   *′ indicates a binding site to T₁, and     -   *″ indicates a binding site to T₂.

In one or more embodiments, a group represented by

in Formula 1 may be a group represented by one of Formulae CY3-1 to CY3-9:

wherein, in Formulae CY3-1 to CY3-9,

-   -   Y₃ may be C or N,     -   R₃₁ to R₃₆ may each independently be as described in connection         with R₃₁,     -   * indicates a binding site to M or A₃,     -   *′ indicates a binding site to T₃, and     -   *″ indicates a binding site to T₂.

In one or more embodiments, at least one of R₃₁ to R₃₆ in Formulae CY3-1 to CY3-9 may not be hydrogen. For example, in one or more embodiments, R₃₄ may not be hydrogen.

In one or more embodiments, a group represented by

in Formula 1 may be a group represented by one of Formulae CY4-1 to CY4-29:

wherein, in Formulae CY4-1 to CY4-29,

-   -   Y₄ may be C or N,     -   Y₄₁ may be N(R_(41a)), O, Se, C(R_(41a))(R_(41b)), or         Si(R_(41a))(R_(41b)), and     -   R₄₁ to R₅₀, R_(41a), and R_(41b) may each independently be as         described in connection with R₄,     -   * indicates a binding site to M or A₄, and     -   *′ indicates a binding site to T₃.

In one or more embodiments, the organometallic compound represented by Formula 1 may be represented by one of Formulae 1-1 to 1-3:

wherein, in Formulae 1-1 to 1-3,

-   -   M, ring CY₂, ring CY₃₁, ring CY₃₂, ring CY₄, Y₂ to Y₄, A₂ to A₄,         T₁ to T₃, R₁₁ to R₁₃, R₂, R₃₁, R₃₂, R₄, d2, d31, d32, and d4 may         each be as described herein.

In one or more embodiments, the organometallic compound represented by Formula 1 may be represented by one of Formulae 1-11 to 1-13:

wherein, in Formulae 1-11 to 1-13,

-   -   X₃₁ may be C(R₃₁) or N, X₃₂ may be C(R₃₂) or N, X₃₃ may be         C(R₃₃) or N, X₃₄ may be C(R₃₄) or N, X₃₅ may be C(R₃₅) or N, and         X₃₆ may be C(R₃₆) or N,     -   X₄₁ may be C(R₄₁) or N, X₄₂ may be C(R₄₂) or N, X₄₃ may be         C(R₄₃) or N, and X₄₄ may be C(R₄₄) or N,     -   R₃₁ to R₃₆ may each be as described in connection with R₃₁,     -   R₄₁ to R₄₄ may each be as described in connection with R₄, and     -   M, ring CY₂, Y₂ to Y₄, A₂ to A₄, T₁ to T₃, R₁₁ to R₁₃, R₂, and         d2 may each be as described herein.

In one or more embodiments, the organometallic compound may be represented by at least one of Compounds 1 to 195, but embodiments are not limited thereto:

The organometallic compound represented by Formula 1 has a structure including at least three nitrogen atoms and a ligand including a carbazole moiety and a 5-membered ring moiety including a carbene structure.

Without wishing to be bound to theory, since the organometallic compound has at least three nitrogen atoms and a 5-membered ring moiety including a carbene structure, the organometallic compound may have a deep highest occupied molecular orbital (HOMO) energy level by introducing nitrogen with strong electronegativity, while maintaining a deep blue emission area. Thus, hole injection may be facilitated, so that the organometallic compound may have a low driving voltage.

Also, and without wishing to be bound to theory, since the organometallic compound includes a carbazole moiety, the organometallic compound may have increased stability against hole injection and light-emitting ability in a deep blue area. In addition, by controlling a three-dimensional structure, it is possible to reduce a bathochromic shift due to intermolecular interaction, which is observed mainly in a planar structure.

Synthesis methods of the organometallic compound represented by Formula 1 may be recognizable by one of ordinary skill in the art and by referring to Synthesis Examples provided below.

The HOMO energy level, lowest unoccupied molecular orbital (LUMO) energy level, T₁ energy level, and maximum emission wavelength (λ_(max)) some compounds of the organometallic compound represented by Formula 1 according one or more embodiments and Comparative Compounds C₁ and C₂ were calculated using a density functional theory (DFT) method of the Gaussian 09 program with the molecular structure optimized at the B3LYP level, and results thereof are shown in Table 1. The energy levels are expressed in electron volts (eV).

TABLE 1 Maximum emission Compound HOMO LUMO T₁ wavelength (λ_(max)) No. (eV) (eV) (eV) (nm)    1 −4.68 −1.19 2.72 456 11 −4.64 −1.17 2.70 460 21 −4.71 −1.22 2.72 452  5 −4.82 −1.31 2.77 450 16 −4.84 −1.31 2.72 452 C1 −4.58 −1.21 2.68 463 C2 −4.94 −1.52 2.46 491

Referring to Table 1, the organometallic compounds according to one or more embodiments were found to have a higher T₁ energy level and a maximum emission wavelength that is blue-shifted, as compared with Comparative Compound C2. Thus, the organometallic compound may have suitable electrical characteristics for use as a material for an emission layer of an organic light-emitting device, for example, as a blue luminescent material. In addition, the organometallic compound had a deeper HOMO energy level, as compared with Compound C1. Thus, hole injection may be facilitated, so that the driving voltage of an organic light-emitting device may be lowered.

Accordingly, another aspect provides an organic light-emitting device including a first electrode; a second electrode; and an organic layer arranged between the first electrode and the second electrode, wherein the organic layer includes an emission layer, and wherein the organic layer further includes at least one organometallic compound described herein.

Since the organic light-emitting device has an organic layer including at least one of the organometallic compounds described herein, the organic light-emitting device may have a low driving voltage, a high efficiency, a high luminance, a high quantum efficiency, and/or a long lifespan.

The expression “(an organic layer) includes at least one organometallic compound” as used herein may include a case in which “(an organic layer) includes identical organometallic compounds represented by Formula 1” and a case in which “(an organic layer) includes two or more different organometallic compounds represented by Formula 1”.

For example, the organic layer may include, as the at least one organometallic compound, only Compound 1. In this regard, Compound 1 may be present in the emission layer of the organic light-emitting device. In one or more embodiments, the organic layer may include, as the at least one organometallic compound, Compound 1 and Compound 2. In this regard, Compound 1 and Compound 2 may be present in an identical layer (for example, both Compound 1 and Compound 2 may be present in the emission layer).

In one or more embodiments, the at least one organometallic compound may be included in the emission layer of the organic light-emitting device.

The at least one organometallic compound included in the emission layer may serve as an emitter. For example, the emission layer including the at least one organometallic compound represented by Formula 1 may emit phosphorescent light that is generated by transition of triplet excitons of the organometallic compound to a ground state.

In one or more embodiments, the emission layer of the organic light-emitting device may further include a host, and an amount of the host in the emission layer may be greater than an amount of the organometallic compound in the emission layer, based on a total weight of the emission layer.

For example, the emission layer of the organic light-emitting device may include a host and a dopant, and the dopant may include the at least one organometallic compound. The host may be selected from suitable hosts. That is, the organometallic compound may serve as a dopant. The emission layer may emit light having a maximum emission wavelength of about 440 nm to about 480 nm, for example, about 440 nm to about 470 nm. For example, the emission layer may emit a blue light.

In one or more embodiments, the emission layer may include a host and a dopant, the host may be any suitable host, and the dopant may include at least one of the organometallic compounds represented by Formula 1, and the emission layer may further include a fluorescent dopant. The emission layer may emit a fluorescent light that is generated by transfer of the triplet excitons of the at least one organometallic compound to the fluorescent dopant, and then a resulting electronic transition thereof.

The first electrode may be an anode, which is a hole injection electrode, and the second electrode may be a cathode, which is an electron injection electrode. In one or more embodiments, the first electrode may be a cathode, which is an electron injection electrode, and the second electrode may be an anode, which is a hole injection electrode.

In one or more embodiments, the first electrode may be an anode, the second electrode may be a cathode, and the organic layer may include a hole transport region arranged between the first electrode and the emission layer, and an electron transport region arranged between the emission layer and the second electrode, wherein the hole transport region may include a hole injection layer, a hole transport layer, an electron blocking layer, or a combination thereof, and the electron transport region may include a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof.

For example, the at least one organometallic compound may be included in at least one of the hole transport region and the electron transport region.

Another aspect provides an electronic apparatus including the organic light-emitting device as described herein.

Description of FIG. 1

FIG. 1 is a schematic cross-sectional view of an organic light-emitting device 10 according to one or more embodiments. Hereinafter, the structure and manufacturing method of the organic light-emitting device 10 according to one or more embodiments will be described in further detail with reference to FIG. 1 .

The organic light-emitting device 10 of FIG. 1 includes a first electrode 11, an organic layer 15, and a second electrode 19, which are sequentially stacked in this stated order.

A substrate may be additionally arranged under the first electrode 11 or above the second electrode 19. For use as the substrate, any substrate that is used in organic light-emitting devices available in the art may be used, and the substrate may be a glass substrate or a transparent plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and/or water resistance.

The first electrode 11 may be, for example, formed by depositing or sputtering a material for forming the first electrode 11 on the substrate. The first electrode 11 may be an anode. The material for forming the first electrode 11 may be selected from materials with a high work function to facilitate hole injection.

The first electrode 11 may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for forming the first electrode 11 may be indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO₂), or zinc oxide (ZnO). In one or more embodiments, the material for forming the first electrode 11 may be a metal, such as magnesium (Mg), aluminum (Al), silver (Ag), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag).

The first electrode 11 may have a single-layered structure or a multi-layered structure including a plurality of layers. For example, the first electrode 11 may have a three-layered structure of ITO/Ag/ITO, but embodiments are not limited thereto.

The organic layer 15 is arranged on the first electrode 11.

The organic layer 15 may include a hole transport region, an emission layer, and an electron transport region.

The hole transport region may be arranged between the first electrode 11 and the emission layer.

The hole transport region may include at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a buffer layer, or a combination thereof.

The hole transport region may include only a hole injection layer or only a hole transport layer. In one or more embodiments, the hole transport region may have a hole injection layer/hole transport layer structure or a hole injection layer/hole transport layer/electron blocking layer structure, wherein, for each structure, respective layers are sequentially stacked in this stated order from the first electrode 11.

When the hole transport region includes a hole injection layer, the hole injection layer may be formed on the first electrode 11 by using one or more suitable methods, such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) deposition, or the like.

When the hole injection layer is formed by vacuum deposition, the deposition conditions may vary according to a material that is used to form the hole injection layer, and the structure and thermal characteristics of the hole injection layer. For example, the deposition conditions may include a deposition temperature of about 100° C. to about 500° C., a vacuum pressure in a range of about 10⁻⁸ torr to about 10⁻³ torr, and a deposition rate in a range of about 0.01 angstroms per second (Å/sec) to about 100 Å/sec, but embodiments are not limited thereto.

When the hole injection layer is formed by spin coating, the coating conditions may vary according to a material that is used to form the hole injection layer, and the structure and thermal characteristics of the hole injection layer. For example, the coating conditions may include a coating speed in a range of about 2,000 revolutions per minute (rpm) to about 5,000 rpm and a heat treatment for removing a solvent after coating at a temperature of about 80° C. to about 200° C., but embodiments are not limited thereto.

Conditions for forming the hole transport layer and the electron blocking layer may be similar to or the same as the conditions for forming the hole injection layer.

The hole transport region may include, for example, at least one of 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDATA), 4,4′,4″-tris{N-(2-naphthyl)-N-phenylamino}-triphenylamine (2-TNATA), N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB), β-NPB, N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine (TPD), spiro-TPD, Spiro-NPB, methylated NPB, 4,4′-cyclohexylidene bis[N,N-bis(4-methylphenyl)benzenamine] (TAPC), 4,4′-bis[N,N′-(3-tolyl)amino]-3,3′-dimethylbiphenyl (HMTPD), 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), polyaniline/camphor sulfonic acid (PANI/CSA), (polyaniline)/poly(4-styrenesulfonate) (PANI/PSS), a compound represented by Formula 201, or a compound represented by Formula 202, but embodiments are not limited thereto:

wherein, in Formula 201, Ar₁₀₁ and Ar₁₀₂ may each independently be a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an acenaphthylene group, a fluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, or a pentacenylene group, each unsubstituted or substituted with at least one of deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₁-C₆₀ alkylthio group, a C₃-C₁₀ cycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₇-C₆₀ aryl alkyl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a C₂-C₆₀ heteroaryl alkyl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, or a combination thereof.

xa and xb in Formula 201 may each independently be an integer from 0 to 5, or may each independently be 0, 1, or 2. For example, xa may be 1 and xb may be 0, but embodiments are not limited thereto.

R₁₀₁ to R₁₀₈, R₁₁₁ to R₁₁₉, and R₁₂₁ to R₁₂₄ in Formulae 201 and 202 may each independently be:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a         cyano group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group         (for example, a methyl group, an ethyl group, a propyl group, a         butyl group, pentyl group, a hexyl group, or the like), a C₁-C₁₀         alkoxy group (for example, a methoxy group, an ethoxy group, a         propoxy group, a butoxy group, a pentoxy group, or the like), or         a C₁-C₁₀ alkylthio group;     -   C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, or a C₁-C₁₀ alkylthio         group, each unsubstituted or substituted with at least one of         deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano         group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, or a combination         thereof; or     -   a phenyl group, a naphthyl group, an anthracenyl group, a         fluorenyl group, or a pyrenyl group, each unsubstituted or         substituted with at least one of deuterium, —F, —Cl, —Br, —I,         —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino         group, an amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a C₁-C₁₀ alkylthio         group, or a combination thereof.

R₁₀₉ in Formula 201 may be a phenyl group, a naphthyl group, an anthracenyl group, or a pyridinyl group, each unsubstituted or substituted with at least one of deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkylthio group, a phenyl group, a naphthyl group, an anthracenyl group, a pyridinyl group, or a combination thereof.

In one or more embodiments, the compound represented by Formula 201 may be represented by Formula 201A:

wherein, in Formula 201A, R₁₀₁, R₁₁₁, R₁₁₂, and R₁₀₉ may each be as described herein.

For example, the hole transport region may include one of Compounds HT1 to HT20, or a combination thereof, but embodiments are not limited thereto:

A thickness of the hole transport region may be about 100 angstroms (Å) to about 10,000 Å, for example, about 100 Å to about 1,000 Å. When the hole transport region includes at least one of a hole injection layer and a hole transport layer, a thickness of the hole injection layer may be about 100 Å to about 10,000 Å, for example, about 100 Å to about 1,000 Å, and a thickness of the hole transport layer may be about 50 Å to about 2,000 Å, for example, about 100 Å to about 1,500 Å. When the thicknesses of the hole transport region, the hole injection layer, and the hole transport layer are within these ranges, satisfactory hole transporting characteristics may be obtained without a substantial increase in driving voltage.

The hole transport region may further include, in addition to the materials described above, a charge-generation material for improving conductive properties. The charge-generation material may be homogeneously or non-homogeneously (heterogeneously) dispersed in the hole transport region.

The charge-generation material may be, for example, a p-dopant. The p-dopant may include a quinone derivative, a metal oxide, a cyano group-containing compound, or a combination thereof, but embodiments are not limited thereto. For example, non-limiting examples of the p-dopant may include a quinone derivative, such as tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ), 1,3,4,5,7,8-hexafluorotetracyanonaphthoquinodimethane (F6-TCNQ), or the like; a metal oxide, such as a tungsten oxide, a molybdenum oxide, or the like; or a cyano group-containing compound, such as Compound HT-D1 or Compound HT-D2, but embodiments are not limited thereto:

The hole transport region may further include a buffer layer.

The buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer to increase efficiency.

The emission layer may be formed on the hole transport region by using one or more suitable methods, such as vacuum deposition, spin coating, casting, and/or LB deposition. When the emission layer is formed by vacuum deposition or spin coating, the deposition or coating conditions may be similar to those applied in forming the hole injection layer, though the deposition or coating conditions may vary according to a material that is used to form the emission layer.

The hole transport region may further include an electron blocking layer. The electron blocking layer may include any suitable material available in the art, for example, 1,3-bis(N-carbazolyl)benzene (mCP), but embodiments are not limited thereto:

A thickness of the electron blocking layer may be about 50 Å to about 1,000 Å, for example, about 70 Å to about 500 Å. When the thickness of the electron blocking layer is within this range, satisfactory electron blocking characteristics may be obtained without a substantial increase in driving voltage.

When the organic light-emitting device 10 is a full-color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and/or a blue emission layer. In one or more embodiments, due to a stacked structure including a red emission layer, a green emission layer, and/or a blue emission layer, the emission layer may emit a white light, and various modifications are possible.

The emission layer may include at least one of the organometallic compounds represented by Formula 1.

The emission layer may include a host and a dopant, and the dopant may include at least one of the organometallic compounds represented by Formula 1.

The host may include 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi), 3-tert-butyl-9,10-di(naphth-2-yl)anthracene (TBADN), 9,10-di(naphthalene-2-yl)anthracene (ADN) (also referred to as “DNA”), 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), 4,4′-bis(9-carbazolyl)-2,2′-dimethyl-biphenyl (CDBP), 1,3,5-tris(carbazole-9-yl)benzene (tCP), 1,3-bis(N-carbazolyl)benzene (mCP), Compound H50, Compound H51, Compound H52, or a combination thereof, but embodiments are not limited thereto:

In one or more embodiments, the host may further include a compound represented by Formula 301:

wherein, in Formula 301, Ar₁₁₁ and Ar₁₁₂ may each independently be:

-   -   a phenylene group, a naphthylene group, a phenanthrenylene         group, or a pyrenylene group; or     -   a phenylene group, a naphthylene group, a phenanthrenylene         group, or a pyrenylene group, each substituted with at least one         of a phenyl group, a naphthyl group, an anthracenyl group, or a         combination thereof.

Ar₁₁₃ to Ar₁₁₆ in Formula 301 may each independently be:

-   -   a C₁-C₁₀ alkyl group, a phenyl group, a naphthyl group, a         phenanthrenyl group, or a pyrenyl group; or     -   a phenyl group, a naphthyl group, a phenanthrenyl group, or a         pyrenyl group, each substituted with at least one of a phenyl         group, a naphthyl group, an anthracenyl group, or a combination         thereof.

g, h, i, and j in Formula 301 may each independently be 0, 1, 2, 3, or 4. For example, g, h, i, and j in Formula 301 may each independently be 0, 1, or 2.

Ar₁₁₃ to Ar₁₁₆ in Formula 301 may each independently be:

-   -   a C₁-C₁₀ alkyl group substituted with at least one of a phenyl         group, a naphthyl group, an anthracenyl group, or a combination         thereof;     -   a phenyl group, a naphthyl group, an anthracenyl group, a         pyrenyl group, a phenanthrenyl group, or a fluorenyl group;     -   a phenyl group, a naphthyl group, an anthracenyl group, a         pyrenyl group, a phenanthrenyl group, or a fluorenyl group, each         substituted with at least one of deuterium, —F, —Cl, —Br, —I,         —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino         group, an amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, a C₁-C₆₀ alkoxy group, a C₁-C₆₀ alkylthio group, a phenyl         group, a naphthyl group, an anthracenyl group, a pyrenyl group,         a phenanthrenyl group, a fluorenyl group, or a combination         thereof; or     -   a compound represented by the formula:

but embodiments are not limited thereto.

In one or more embodiments, the host may include a compound represented by Formula 302:

wherein, in Formula 302, Ar₁₂₂ to Ar₁₂₅ may each be as described in connection with Ar₁₁₃ in Formula 301.

Ar₁₂₆ and Ar₁₂₇ in Formula 302 may each independently be a C₁-C₁₀ alkyl group (for example, a methyl group, an ethyl group, a propyl group, or the like).

k and l in Formula 302 may each independently be an integer of 0, 1, 2, 3, or 4. For example, k and l in Formula 302 may each independently be 0, 1, or 2.

When the organic light-emitting device 10 is a full-color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and/or a blue emission layer. In one or more embodiments, due to a stacked structure including a red emission layer, a green emission layer, and/or a blue emission layer, the emission layer may emit a white light, and various modifications are possible.

When the emission layer includes a host and a dopant, an amount of the dopant may be about 0.01 part by weight to about 20 parts by weight, based on 100 parts by weight of the emission layer, but embodiments are not limited thereto. When the amount of the dopant is within this range, light emission without quenching may be realized.

In one or more embodiments, the organic layer 15 of the organic light-emitting device 10 may further include, in addition to the at least one organometallic compound represented by Formula 1, at least one fluorescent dopant.

For example, the at least one fluorescent dopant may be a condensed polycyclic compound, a styryl-based compound, or a combination thereof.

In one or more embodiments, the fluorescent dopant may be a compound represented by Formula 501:

wherein, in Formula 501,

-   -   Ar₅₀₁ may be:     -   a naphthalene group, a fluorene group, a spiro-bifluorene group,         a benzofluorene group, a dibenzofluorene group, a phenanthrene         group, an anthracene group, a fluoranthene group, a triphenylene         group, a pyrene group, a chrysene group, a naphthacene group, a         picene group, a perylene group, a pentaphene group, an         indenoanthracene group, a tetracene group, a bisanthracene         group, or a group represented by one of Formulae 501-1 to         501-18; or a naphthalene group, a fluorene group, a         spiro-bifluorene group, a benzofluorene group, a dibenzofluorene         group, a phenanthrene group, an anthracene group, a fluoranthene         group, a triphenylene group, a pyrene group, a chrysene group, a         naphthacene group, a picene group, a perylene group, a         pentaphene group, an indenoanthracene group, a tetracene group,         a bisanthracene group, or a group represented by one of Formulae         501-1 to 501-18, each substituted with at least one of         deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano         group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy         group, a C₁-C₆₀ alkylthio group, a C₃-C₁₀ cycloalkyl group, a         C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀         alkyl aryl group, a C₇-C₆₀ aryl alkyl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₂-C₆₀ alkyl heteroaryl group, a C₂-C₆₀ heteroaryl alkyl group,         a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a         monovalent non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group,         —Si(Q₅₀₁)(Q₅₀₂)(Q₅₀₃) (wherein Q₅₀₁ to Q₅₀₃ may each         independently be hydrogen, a C₁-C₆₀ alkyl group, a C₁-C₆₀ alkoxy         group, a C₁-C₆₀ alkylthio group, a C₆-C₆₀ aryl group, a C₇-C₆₀         alkyl aryl group, a C₇-C₆₀ aryl alkyl group, a C₁-C₆₀ heteroaryl         group, a C₂-C₆₀ alkyl heteroaryl group, a C₂-C₆₀ heteroaryl         alkyl group, a monovalent non-aromatic condensed polycyclic         group, or a monovalent non-aromatic condensed heteropolycyclic         group), or a combination thereof,     -   L₅₀₁ to L₅₀₃ may each independently be a substituted or         unsubstituted C₃-C₁₀ cycloalkylene group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkylene group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenylene group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenylene group, a substituted         or unsubstituted C₆-C₆₀ arylene group, a substituted or         unsubstituted C₁-C₆₀ heteroarylene group, a substituted or         unsubstituted divalent non-aromatic condensed polycyclic group,         or a substituted or unsubstituted divalent non-aromatic         condensed heteropolycyclic group,

R₅₀₁ and R₅₀₂ may each independently be:

-   -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-bifluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, a chrysenyl group,         a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazole group, a         triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl         group; or     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-bifluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, a chrysenyl group,         a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a         triazinyl group, a dibenzofuranyl group, or a dibenzothiophenyl         group, each substituted with at least one of deuterium, —F, —Cl,         —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group,         an amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a C₁-C₂₀         alkylthio group, a phenyl group, a biphenyl group, a terphenyl         group, a naphthyl group, a fluorenyl group, a spiro-bifluorenyl         group, a benzofluorenyl group, a dibenzofluorenyl group, a         phenanthrenyl group, an anthracenyl group, a pyrenyl group, a         chrysenyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group,         a carbazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, or a combination thereof,     -   xd1 to xd3 may each independently be 0, 1, 2, or 3, and     -   xd4 may be 0, 1, 2, 3, 4, 5, or 6.

For example, in Formula 501,

Ar₅₀₁ may be:

-   -   a naphthalene group, a fluorene group, a spiro-bifluorene group,         a benzofluorene group, a dibenzofluorene group, a phenanthrene         group, an anthracene group, a fluoranthene group, a triphenylene         group, a pyrene group, a chrysene group, a naphthacene group, a         picene group, a perylene group, a pentaphene group, an         indenoanthracene group, a tetracene group, a bisanthracene         group, or a group represented by one of Formulae 501-1 to         501-18; or     -   a naphthalene group, a fluorene group, a spiro-bifluorene group,         a benzofluorene group, a dibenzofluorene group, a phenanthrene         group, an anthracene group, a fluoranthene group, a triphenylene         group, a pyrene group, a chrysene group, a naphthacene group, a         picene group, a perylene group, a pentaphene group, an         indenoanthracene group, a tetracene group, a bisanthracene         group, or a group represented by one of Formulae 501-1 to         501-18, each substituted with at least one of deuterium, —F,         —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro         group, an amino group, an amidino group, a hydrazine group, a         hydrazone group, a carboxylic acid group or a salt thereof, a         sulfonic acid group or a salt thereof, a phosphoric acid group         or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group,         a C₁-C₂₀ alkylthio group, a phenyl group, a biphenyl group, a         terphenyl group, a naphthyl group, a fluorenyl group, a         dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl         group, a pyridinyl group, a pyrimidinyl group, a triazinyl         group, a quinolinyl group, an isoquinolinyl group,         —Si(Q₅₀₁)(Q₅₀₂)(Q₅₀₃) (wherein Q₅₀₁ to Q₅₀₃ may each         independently be hydrogen, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy         group, a C₁-C₂₀ alkylthio group, a phenyl group, a biphenyl         group, a terphenyl group, or a naphthyl group), or a combination         thereof,

-   -   L₅₀₁ to L₅₀₃ are each as described in connection with L₂₁,     -   xd1 to xd3 may each independently be 0, 1, or 2, and     -   xd4 may be 0, 1, 2, or 3, but embodiments are not limited         thereto.

The fluorescent dopant may include, for example, at least one of Compounds FD(1) to FD(16), Compounds FD1 to FD13, or a combination thereof, but embodiments are not limited thereto:

A thickness of the emission layer may be about 100 Å to about 1,000 Å, for example, about 200 Å to about 600 Å. When the thickness of the emission layer is within this range, excellent luminescence characteristics may be obtained without a substantial increase in driving voltage.

Next, the electron transport region may be arranged on the emission layer.

The electron transport region may include at least one of a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof.

For example, the electron transport region may have a hole blocking layer/electron transport layer/electron injection layer structure or an electron transport layer/electron injection layer structure, but embodiments are not limited thereto. The electron transport layer may have a single-layered structure or a multi-layered structure including two or more different materials.

Conditions for forming the hole blocking layer, the electron transport layer, and the electron injection layer which constitute the electron transport region may be similar to or the same as the conditions for forming the hole injection layer.

When the electron transport region includes a hole blocking layer, the hole blocking layer may include, for example, at least one of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) or 4,7-diphenyl-1,10-phenanthroline (Bphen), but embodiments are not limited thereto:

A thickness of the hole blocking layer may be about 20 Å to about 1,000 Å, for example, about 30 Å to about 300 Å. When the thickness of the hole blocking layer is within this range, excellent hole blocking characteristics may be obtained without a substantial increase in driving voltage.

The electron transport layer may include at least one of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), tris(8-hydroxy-quinolinato)aluminum (Alq₃), bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-biphenyl-4-olato)aluminum (BAlq), 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), or 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), but embodiments are not limited thereto:

In one or more embodiments, the electron transport layer may include at least one of Compounds ET1 to ET25, but embodiments are not limited thereto:

A thickness of the electron transport layer may be about 100 Å to about 1,000 Å, for example, about 150 Å to about 500 Å. When the thickness of the electron transport layer is within this range, satisfactory electron transporting characteristics may be obtained without a substantial increase in driving voltage.

The electron transport layer may include, in addition to the materials described herein, a metal-containing material.

The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (lithium quinolate, LiQ) or ET-D2, but embodiments are not limited thereto:

The electron transport region may include an electron injection layer that facilitates injection of electrons from the second electrode 19.

The electron injection layer may include at least one of LiQ, LiF, NaCl, CsF, Li₂O, or BaO, but embodiments are not limited thereto.

A thickness of the electron injection layer may be about 1 Å to about 100 Å, for example, about 3 Å to about 90 Å. When the thickness of the electron injection layer is within this range, satisfactory electron injection characteristics may be obtained without a substantial increase in driving voltage.

The second electrode 19 may be arranged on the organic layer 15. The second electrode 19 may be a cathode. A material for forming the second electrode 19 may be a metal, an alloy, an electrically conductive compound, or a combination thereof, each of which may have a relatively low work function. For example, the material for forming the second electrode 19 may be lithium (Li), magnesium (Mg), aluminum (Al), silver (Ag), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag). In one or more embodiments, to manufacture a top-emission type light-emitting device, a transmissive electrode formed using ITO or IZO may be used as the second electrode 19.

Hereinbefore, the organic light-emitting device 10 has been described with reference to FIG. 1 , but embodiments are not limited thereto.

According to another aspect, the organic light-emitting device may be included in an electronic apparatus. Thus, an electronic apparatus including the organic light-emitting device is provided. The electronic apparatus may include, for example, a display, an illumination, a sensor, or the like, but embodiments are not limited thereto.

EXPLANATION OF TERMS

The term “C₁-C₆₀ alkyl group” as used herein refers to a linear or branched saturated aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms, and non-limiting examples thereof may include a methyl group, an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isoamyl group, a hexyl group, or the like. The term “C₁-C₆₀ alkylene group” as used herein refers to a divalent group having the same structure as the C₁-C₆₀ alkyl group.

The term “C₁-C₆₀ alkoxy group” as used herein refers to a monovalent group represented by —OA₁₀₁ (wherein A₁₀₁ is the C₁-C₆₀ alkyl group), and non-limiting examples thereof may include a methoxy group, an ethoxy group, an isopropyloxy group, or the like.

The term “C₂-C₆₀ alkenyl group” as used herein refers to a hydrocarbon group formed by substituting at least one carbon-carbon double bond in the middle or at the terminus of the C₂-C₆₀ alkyl group, and non-limiting examples thereof may include an ethenyl group, a propenyl group, a butenyl group, or the like. The term “C₂-C₆₀ alkenylene group” as used herein refers to a divalent group having the same structure as the C₂-C₆₀ alkenyl group.

The term “C₂-C₆₀ alkynyl group” as used herein refers to a hydrocarbon group formed by substituting at least one carbon-carbon triple bond in the middle or at the terminus of the C₂-C₆₀ alkyl group, and non-limiting examples thereof may include an ethynyl group, a propynyl group, or the like. The term “C₂-C₆₀ alkynylene group” as used herein refers to a divalent group having the same structure as the C₂-C₆₀ alkynyl group.

The term “C₃-C₁₀ cycloalkyl group” as used herein refers to a monovalent saturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, and non-limiting examples thereof may include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, or the like. The term “C₃-C₁₀ cycloalkylene group” as used herein refers to a divalent group having the same structure as the C₃-C₁₀ cycloalkyl group.

The term “C₁-C₁₀ heterocycloalkyl group” as used herein refers to a monovalent monocyclic group including at least one heteroatom selected from B, N, O, P, Si, Ge, Se, and S as a ring-forming atom and 1 to 10 carbon atoms as ring forming atom(s), and non-limiting examples thereof may include a tetrahydrofuranyl group, a tetrahydrothiophenyl group, or the like. The term “C₁-C₁₀ heterocycloalkylene group” as used herein refers to a divalent group having the same structure as the C₁-C₁₀ heterocycloalkyl group.

The term “C₃-C₁₀ cycloalkenyl group” as used herein refers to a monovalent monocyclic group that has 3 to 10 carbon atoms and at least one carbon-carbon double bond in the ring thereof and no aromaticity, and non-limiting examples thereof may include a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, or the like. The term “C₃-C₁₀ cycloalkenylene group” as used herein refers to a divalent group having the same structure as the C₃-C₁₀ cycloalkenyl group.

The term “C₁-C₁₀ heterocycloalkenyl group” as used herein refers to a monovalent monocyclic group that has at least one heteroatom selected from B, N, O, P, Si, Ge, Se, and S as a ring-forming atom, 1 to 10 carbon atoms as ring forming atom(s), and at least one double bond in the ring thereof. Non-limiting examples of the C₁-C₁₀ heterocycloalkenyl group may include a 2,3-dihydrofuranyl group, a 2,3-dihydrothiophenyl group, or the like. The term “C₁-C₁₀ heterocycloalkenylene group” as used herein refers to a divalent group having the same structure as the C₁-C₁₀ heterocycloalkenyl group.

The term “C₆-C₆₀ aryl group” as used herein refers to a monovalent group that includes a carbocyclic aromatic system having 6 to 60 carbon atoms, and the term “C₆-C₆₀ arylene group” as used herein refers to a divalent group that includes a carbocyclic aromatic system having 6 to 60 carbon atoms. Non-limiting examples of the C₆-C₆₀ aryl group may include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, a chrysenyl group, or the like. When the C₆-C₆₀ aryl group and the C₆-C₆₀ arylene group each include two or more rings, the two or more rings may be fused to each other.

The term “C₁-C₆₀ heteroaryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system having at least one heteroatom selected from B, N, O, P, Si, Ge, Se, and S as a ring-forming atom and 1 to 60 carbon atoms as ring forming atom(s). The term “C₁-C₆₀ heteroarylene group” as used herein refers to a divalent group having a carbocyclic aromatic system having at least one heteroatom selected from B, N, O, P, Si, Ge, Se, and S as a ring-forming atom and 1 to 60 carbon atoms as ring forming atom(s). Non-limiting examples of the C₁-C₆₀ heteroaryl group may include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, an isoquinolinyl group, or the like. When the C₁-C₆₀ heteroaryl group and the C₁-C₆₀ heteroarylene group each include two or more rings, the two or more rings may be fused to each other.

The term “C₇-C₆₀ alkyl aryl group” as used herein refers to a C₆-C₆₀ aryl group substituted with at least one C₁-C₆₀ alkyl group. The term “C₇-C₆₀ aryl alkyl group” as used herein refers to a C₁-C₆₀ alkyl group substituted with at least one C₆-C₆₀ aryl group.

The term “C₂-C₆₀ alkyl heteroaryl group” as used herein refers to a C₁-C₆₀ heteroaryl group substituted with at least one C₁-C₆₀ alkyl group. The term “C₂-C₆₀ heteroaryl alkyl group” as used herein refers to a C₁-C₆₀ alkyl group substituted with at least one C₁-C₆₀ heteroaryl group.

The term “C₆-C₆₀ aryloxy group” as used herein refers to —OA₁₀₂ (wherein A₁₀₂ is the C₆-C₆₀ aryl group), and the term “C₆-C₆₀ arylthio group” as used herein refers to —SA₁₀₃ (wherein A₁₀₃ is the C₆-C₆₀ aryl group).

The term “C₁-C₆₀ heteroaryloxy group” as used herein indicates —OA₁₀₄ (wherein A₁₀₄ is a C₁-C₆₀ heteroaryl group), and the term “C₁-C₆₀ heteroarylthio group” as used herein indicates —SA₁₀₅ (wherein A₁₀₅ is the C₁-C₆₀ heteroaryl group).

The term “monovalent non-aromatic condensed polycyclic group” as used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) having two or more rings condensed to each other, only carbon atoms as ring-forming atoms, and no aromaticity in its entire molecular structure. Non-limiting examples of the monovalent non-aromatic condensed polycyclic group may include a fluorenyl group or the like. The term “divalent non-aromatic condensed polycyclic group” as used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed polycyclic group.

The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein refers to a monovalent group (for example, having 2 to 60 carbon atoms) having two or more rings condensed with each other, at least one heteroatom selected from B, N, O, P, Si, Ge, Se, and S, other than carbon atoms, as a ring-forming atom, and no aromaticity in its entire molecular structure. Non-limiting examples of the monovalent non-aromatic condensed heteropolycyclic group may include a carbazolyl group or the like. The term “divalent non-aromatic condensed heteropolycyclic group” as used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed heteropolycyclic group.

The term “C₅-C₃₀ carbocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, 5 to 30 carbon atoms only. The C₅-C₃₀ carbocyclic group may be a monocyclic group or a polycyclic group.

The term “C₁-C₃₀ heterocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, at least one heteroatom selected from N, O, Si, P, and S other than 1 to 30 carbon atoms as ring forming atom(s). The C₁-C₃₀ heterocyclic group may be a monocyclic group or a polycyclic group.

At least one substituent of the substituted C₅-C₃₀ carbocyclic group, the substituted C₁-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₁-C₆₀ alkylthio group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₇-C₆₀ alkyl aryl group, the substituted C₇-C₆₀ aryl alkyl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group, the substituted C₂-C₆₀ alkyl heteroaryl group, the substituted C₂-C₆₀ heteroaryl alkyl group, the substituted C₁-C₆₀ heteroaryloxy group, the substituted C₁-C₆₀ heteroarylthio group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be:

-   -   deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃,         —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, a C₁-C₆₀ alkoxy group, or a C₁-C₆₀ alkylthio group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, a C₁-C₆₀ alkoxy group, or a C₁-C₆₀ alkylthio group, each         substituted with at least one of deuterium, —F, —Cl, —Br, —I,         —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group,         a cyano group, a nitro group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a         C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀         alkyl aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl heteroaryl         group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio         group, a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group,         —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), —Ge(Q₁₃)(Q₁₄)(Q₁₅),         —B(Q₁₆)(Q₁₇), —P(Q₁₈)(Q₁₉), or —P(═O)(Q₁₈)(Q₁₉);     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group,     -   a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀         heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a C₁-C₆₀         heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent         non-aromatic condensed polycyclic group, or a monovalent         non-aromatic condensed heteropolycyclic group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy         group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a         C₂-C₆₀ alkyl heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a         C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed         polycyclic group, and a monovalent non-aromatic condensed         heteropolycyclic group, each substituted with at least one of         deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃,         —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, a C₁-C₆₀ alkoxy group, a C₁-C₆₀ alkylthio group, a C₃-C₁₀         cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀         cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀         aryl group, a C₇-C₆₀ alkyl aryl group, a C₇-C₆₀ aryl alkyl         group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀         heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a C₂-C₆₀         heteroaryl alkyl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀         heteroarylthio group, a monovalent non-aromatic condensed         polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),         —Ge(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), —P(Q₂₈)(Q₂₉) or         —P(═O)(Q₂₈)(Q₂₉), or     -   —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —Ge(Q₃₃)(Q₃₄)(Q₃₅),         —B(Q₃₆)(Q₃₇), —P(Q₃₈)(Q₃₉), or —P(═O)(Q₃₈)(Q₃₉), and     -   Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ may each         independently be hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, a         hydroxyl group, a cyano group, a nitro group, an amino group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted         or unsubstituted C₂-C₆₀ alkenyl group, a substituted or         unsubstituted C₂-C₆₀ alkynyl group, a substituted or         unsubstituted C₁-C₆₀ alkoxy group, a substituted or         unsubstituted C₁-C₆₀ alkylthio group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₇-C₆₀ alkyl aryl group, a substituted or unsubstituted C₇-C₆₀         aryl alkyl group, a substituted or unsubstituted C₆-C₆₀ aryloxy         group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a         substituted or unsubstituted C₁-C₆₀ heteroaryl group, a         substituted or unsubstituted C₂-C₆₀ alkyl heteroaryl group, a         substituted or unsubstituted C₂-C₆₀ heteroaryl alkyl group, a         substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a         substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a         substituted or unsubstituted monovalent non-aromatic condensed         polycyclic group, or a substituted or unsubstituted monovalent         non-aromatic condensed heteropolycyclic group.

For example, Q₁ to Q, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ as used herein may each independently be:

-   -   —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂,         —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, or         —CD₂CDH₂, or     -   an n-propyl group, an isopropyl group, an n-butyl group, a         sec-butyl group, an isobutyl group, a tert-butyl group, an         n-pentyl group, a tert-pentyl group, a neopentyl group, an         isopentyl group, a sec-pentyl group, a 3-pentyl group, a         sec-isopentyl group, a phenyl group, a biphenyl group, or a         naphthyl group, each unsubstituted or substituted with at least         one of deuterium, a C₁-C₁₀ alkyl group, a phenyl group, or a         combination thereof.

The term “room temperature” as used herein refers to a temperature of about 25° C.

The terms “a biphenyl group, a terphenyl group, and a tetraphenyl group” as used herein each refer to a monovalent group having two, three, and four phenyl groups linked to each other via a single bond, respectively.

Hereinafter, a compound and an organic light-emitting device according to one or more exemplary embodiments will be described in further detail with reference to Synthesis Examples and Examples. However, embodiments are not limited thereto. The wording “‘B’ was used instead of ‘A’” as used in describing Synthesis Examples means that an amount of ‘A’ used was identical to an amount of ‘B’ used, in terms of a molar equivalent.

EXAMPLES Synthesis Example 1: Synthesis of Compound 1

Synthesis of [Compound 1-B]

Compound 1-A (11.5 grams (g), 78.7 millimoles (mmol)), 3-bromoaniline (7.71 milliliters (mL), 70.8 mmol), and trifluoroacetic acid (6.00 mL, 78.7 mmol) were placed in a round-bottom flask, and then mixed with o-dichlorobenzene (75 mL). The resultant reaction solution was stirred and heated under reflux at 185° C. for 12 hours. After completion of the reaction, the temperature was allowed to lower to room temperature, and then, ethyl acetate and a saturated aqueous Na₂CO₃ solution were added to the reaction solution. An organic solution layer was extracted therefrom using ethyl acetate, the organic layer was dried using anhydrous MgSO₄, and then the product was filtered. The filtrate was concentrated and purified through silica gel column chromatography to obtain 5.0 g (yield of 21%) of Compound 1-B.

High performance liquid chromatography-mass spectrometry (HPLC-MS): 301.99 [M+H]⁺.

Synthesis of [Compound 1-D]

Compound 1-B (5.00 g, 16.6 mmol), Compound 1-C (5.80 g, 18.3 mmol), CuI (0.634 g, 3.33 mmol), 2-picolinic acid (0.902 g, 7.33 mmol), and K₃PO₄ (10.6 g, 50.0 mmol) were placed in a round-bottom flask, and then mixed with dimethyl sulfoxide (DMSO) (110 mL). The resultant reaction solution was stirred and heated under reflux at 100° C. for 12 hours. After completion of the reaction, the temperature was allowed to lower to room temperature, and then, ethyl acetate and a saturated aqueous ammonium chloride solution were added to the reaction solution. An organic solution layer was extracted therefrom using ethyl acetate, the organic layer was dried using anhydrous MgSO₄, and then the product was filtered. The filtrate was concentrated under a reduced pressure and purified through silica gel column chromatography to obtain 5.4 g (yield of 49%) of Compound 1-D.

HPLC-MS: 536.21 [M+H]⁺.

Synthesis of [Compound 1-F]

Compound 1-D (4.2 g, 7.80 mmol), Compound 1-E (6.84 g, 11.7 mmol), and copper(II) acetate (Cu(Oac)₂) (0.14 g, 0.780 mmol) were placed in a round-bottom flask, and then mixed with dimethylformamide (DMF) (40 mL). The resultant reaction solution was stirred and heated under reflux at 100° C. for 12 hours. After completion of the reaction, the temperature was allowed to lower to room temperature, and then, ethyl acetate and a saturated aqueous ammonium chloride solution were added to the reaction solution. An organic solution layer was extracted therefrom using ethyl acetate, the organic layer was dried using anhydrous MgSO₄, and then the product was filtered. The filtrate was concentrated under a reduced pressure and purified through silica gel column chromatography to obtain 6.0 g (yield of 88%) of Compound 1-F.

HPLC-MS: 724.36 [M-OTf]⁺.

Synthesis of [Compound 1]

Compound 1-F (6.00 g, 6.86 mmol), dichloro(1,5-cyclooctadiene)platinum(II) (Pt(COD)Cl₂) (2.82 g, 7.55 mmol), and sodium acetate (NaOAc) (1.69 g, 20.6 mmol) were placed in a round-bottom flask, and then mixed with DMF (100 mL). The resultant reaction solution was stirred and heated under reflux at 160° C. for 12 hours. After completion of the reaction, the temperature was allowed to lower to room temperature, and then, the reaction solution was diluted with dichloromethane. The precipitate was filtered using celite/silica, and then, deionized (DI) water was added to the filtrate. An organic solution layer was extracted therefrom using dichloromethane, the organic layer was dried using anhydrous MgSO₄, and then the product was filtered. The filtrate was concentrated under a reduced pressure and purified through silica gel column chromatography to obtain 2.00 g (yield of 32%) of Compound 1.

HPLC-MS: 917.29 [M+H]⁺.

Synthesis Example 2: Synthesis of Compound 11

Synthesis of [Compound 11-B]

Compound 2-A (6.70 g, 22.3 mmol), Compound 1-C(7.77 g, 24.6 mmol), CuI (0.850 g, 4.46 mmol), 2-picolinic acid (1.21 g, 9.82 mmol), and K₃PO₄ (14.2 g, 67.0 mmol) were placed in a round-bottom flask, and then mixed with DMSO (150 mL). The resultant reaction solution was stirred and heated under reflux at 100° C. for 12 hours. After completion of the reaction, the temperature was allowed to lower to room temperature, and then, ethyl acetate and a saturated aqueous ammonium chloride solution were added to the reaction solution. An organic solution layer was extracted therefrom using ethyl acetate, the organic layer was dried using anhydrous MgSO₄, and then the product was filtered. The filtrate was concentrated under a reduced pressure and purified through silica gel column chromatography to obtain 6.3 g (yield of 53%) of Compound 11-B.

HPLC-MS: 536.23 [M+H]⁺.

Synthesis of [Compound 11-C]

Compound 11-B (3.8 g, 7.09 mmol), Compound 1-E (6.22 g, 10.6 mmol), and Cu(OAc)₂ (0.135 g, 0.710 mmol) were placed in a round-bottom flask, and then mixed with DMF (30 mL). The resultant reaction solution was stirred and heated under reflux at 100° C. for 12 hours. After completion of the reaction, the temperature was allowed to lower to room temperature, and then, ethyl acetate and a saturated aqueous ammonium chloride solution were added to the reaction solution. An organic solution layer was extracted therefrom using ethyl acetate, the organic layer was dried using anhydrous MgSO₄, and then the product was filtered. The filtrate was concentrated under a reduced pressure and purified through silica gel column chromatography to obtain 4.0 g (yield of 65%) of Compound 11-C.

HPLC-MS: 724.38 [M-OTf]⁺.

Synthesis of [Compound 11]

Compound 11-C(6.00 g, 6.86 mmol), Pt(COD)Cl₂ (2.82 g, 7.55 mmol), and NaOAc (1.69 g, 20.6 mmol) were placed in a round-bottom flask, and then mixed with DMF (100 mL). The resultant reaction solution was stirred and heated under reflux at 160° C. for 12 hours. After completion of the reaction, the temperature was allowed to lower to room temperature, and then, the reaction solution was diluted with dichloromethane. The precipitate was filtered using celite/silica, and then, DI water was added to the filtrate. An organic solution layer was extracted therefrom using dichloromethane, the organic layer was dried using anhydrous MgSO₄, and then the product was filtered. The filtrate was concentrated and purified through silica gel column chromatography to obtain 2.00 g (yield of 32%) of Compound 11.

HPLC-MS: 917.29 [M+H]⁺.

Evaluation Example 1: Evaluation of Photoluminescence (PL) Spectrum

Compound 1, Compound 11, Comparative Compound C1, and Comparative Compound C2 were each diluted in toluene at a concentration of 104 molar (M). Then, the photoluminescence (PL) spectrum of each compound was measured using an ISC PC1 spectrofluorometer, in which a xenon lamp was mounted, and the results are shown in FIG. 2 . The maximum emission wavelength value (λ_(max), nm) and T₁ energy (eV) of each compound were obtained from the PL spectrum thereof, and the results are shown in Table 2.

In detail, the T₁ energy was converted into an energy level value at the maximum emission wavelength. In addition, the HOMO and LUMO energy levels of each compound were measured by differential pulse voltammetry (DPV). The solvent used for the measurement was DMF, and tetrabutylammonium fluoride (TBAF) was used as an electrolyte. In addition, the reference electrode Ag/Ag+ was used, and the counter electrode Pt and the working electrode Pt were used. During the measurement, ferrocene (Fc) was used as a reference material, and the HOMO of Fc is known to be −4.8 eV. Accordingly, the HOMO and LUMO energy levels of each compound were calculated by applying the potential value measured by DPV to the data calculation method below. The reference data is shown in Table 1A, below.

TABLE 1A Measurement potential Energy level (eV) Ref. α −4.8 HOMO β −4.8-(β − α)  LUMO γ −4.8-(−γ − α)

TABLE 2 HOMO LUMO T₁ λ_(max) Compound (eV) (eV) (eV) (nm)  1 −5.32 −2.01 2.75 451 11 −5.31 −1.98 2.71 458 C1 −5.20 −2.01 2.73 454 C2 −5.18 −2.37 2.57 482

Referring to Table 2, Compounds 1 and 11 according to one or more embodiments were found to emit a deep blue light and have deeper HOMO energy values than Comparative Compounds C1 and C2.

Example 1

An ITO glass substrate was cut to a size of 50 millimeters (mm)×50 mm×0.5 mm, sonicated in acetone, isopropyl alcohol, and DI water, each for 15 minutes, and then washed by exposure to UV ozone for 30 minutes each.

Then, m-MTDATA was deposited on an ITO electrode (anode) on the glass substrate at a deposition rate of 1 Å/sec to form a hole injection layer having a thickness of 600 Å, and then, α-NPD was deposited on the hole injection layer at a deposition rate of 1 Å/sec to form a hole transport layer having a thickness of 250 Å.

Compound 1 (dopant) and CBP (host) were co-deposited on the hole transport layer at a deposition rate of 0.1 Å/sec and a deposition rate of 1 Å/sec, respectively, to form an emission layer having a thickness of 400 Å.

BAlq was deposited on the emission layer at a deposition rate of 1 Å/sec to form a hole blocking layer having a thickness of 50 Å, Alq₃ was deposited on the hole blocking layer to form an electron transport layer having a thickness of 300 Å, LiF was deposited on the electron transport layer to form an electron injection layer having a thickness of 10 Å, and then, Al was vacuum-deposited on the electron injection layer to form a second electrode (cathode) having a thickness of 1,200 Å, thereby completing the manufacture of an organic light-emitting device having a structure of ITO/m-MTDATA (600 Å)/α-NPD (250 Å)/CBP+Compound 1 (10 wt %) (400 Å)/BAlq (50 Å)/Alq₃ (300 Å)/LiF (10 Å)/Al (1,200 Å).

Example 2

An organic light-emitting device was manufactured in a similar manner as in Example 1, except that Compound 11 was used instead of Compound 1 to form an emission layer.

Comparative Example 1

An organic light-emitting device was manufactured in a similar manner as in Example 1, except that Compound C1 was used instead of Compound 1 to form an emission layer.

Comparative Example 2

An organic light-emitting device was manufactured in a similar manner as in Example 1, except that Compound C3 was used instead of Compound 1 to form an emission layer.

Evaluation Example 2: Evaluation of Characteristics of Organic Light-Emitting Devices

The electroluminescence (EL) spectrum of each of the organic light-emitting devices manufactured according to Examples 1 and 2 and Comparative Examples 1 and 2 were measured, and the results are shown in Table 3. Also, a graph of luminance according to voltage of each device is shown in FIG. 4 . The maximum emission wavelength (nm), driving voltage (relative value, %), and external quantum luminescence efficiency (EQE, relative value, %, at 1,000 cd/m²) of each device were evaluated from the EL spectrum thereof, and the results are shown in Table 3. The maximum emission wavelength of the EL spectrum was evaluated from the EL spectrum (at 1,000 cd/m²) measured using a luminance meter (Minolta Cs-1000A) for each of the organic light-emitting devices. The driving voltage and external quantum luminescence efficiency were evaluated using a current-voltmeter (Keithley 2400) and a luminance meter (Minolta Cs-1000A), and were expressed as relative values (%) based on the lowest values.

TABLE 3 Maximum Driving External quantum Dopant emission voltage luminescence compound wavelength (%, relative efficiency (%, No. (nm) value) relative value) Example 1  1 454  83 233 Example 2 11 458  83 274 Comparative C1 456 100 154 Example 1 Comparative C3 461  87 100 Example 2

Referring to Table 3, the organic light-emitting devices of Examples 1 and 2 were found to have lower driving voltages and higher external quantum luminescence efficiencies, as compared with the organic light-emitting devices of Comparative Examples 1 and 2.

By using at least one of the organometallic compounds represented by Formula 1, an organic light-emitting device having excellent luminescence efficiency, and an electronic apparatus including the same was provided.

It should be understood that exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each exemplary embodiment should typically be considered as available for other similar features or aspects in other exemplary embodiments. While one or more exemplary embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims. 

What is claimed is:
 1. An organometallic compound represented by Formula 1:

wherein, in Formula 1, M is a transition metal, X₁₁ is N or C(R₁₁), X₁₂ is N or C(R₁₂), at least one of X₁₁ and X₁₂ is N, ring CY₂, ring CY₃₁, ring CY₃₂, and ring CY₄ are each independently a C₃-C₆₀ carbocyclic group or a C₁-C₆₀ heterocyclic group, Y₂ to Y₄ are each independently C or N, A₂ to A₄ are each independently a chemical bond, O, or S, T₁ is a single bond, a double bond, *—N[(L₁)_(b1)-(R_(1a))]—*′, *—B(R_(1a))—*′, *—P(R_(1a))—*′, *—C(R_(1a))(R_(1b))—*′, *—Si(R_(1a))(R_(1b))—*′, *—Ge(R_(1a))(R_(1b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(1a))═*′, *═C(R_(1a))—*′, *—C(R_(1a))═C(R_(1b))—*′, *—C(═S)—*, or *—C≡C—*′, T₂ is a single bond, a double bond, *—N[(L₂)_(b2)-(R_(2a))]—*′, *—B(R_(2a))—*′, *—P(R_(2a))—*′, *—C(R_(2a))(R_(2b))—*′, *—Si(R_(2a))(R_(2b))—*′, *—Ge(R_(2a))(R_(2b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(2a))═*′, *═C(R_(2a))—*′, *—C(R_(2a))═C(R_(2b))—*′, *—C(═S)—*, or *—C≡C—*′, T₃ is a single bond, a double bond, *—N[(L₃)_(b3)-(R_(3a))]—*′, *—B(R_(3a))—*′, *—P(R_(3a))—*′, *—C(R_(3a))(R_(3b))—*′, *—Si(R_(3a))(R_(3b))—*′, *—Ge(R_(3a))(R_(3b))—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R_(3a))═*′, *═C(R_(3a))—*′, *—C(R_(3a))═C(R_(3b))—*′, *—C(═S)—*, or *—C≡C—*′, a1 to a3 are each independently an integer from 1 to 3, * and *′ each indicate a binding site to a neighboring atom, L₁ to L₃ are each independently a single bond, a C₅-C₃₀ carbocyclic group unsubstituted or substituted with at least one R_(10a), or a C₁-C₃₀ heterocyclic group unsubstituted or substituted with at least one R_(10a), b1 to b3 are each independently an integer from 1 to 3, R_(1a), R_(1b), R₂, R_(2a), R_(2b), R_(3a), R_(3b), R₄, R_(10a), R₁₁ to R₁₃, R₃₁, and R₃₂ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₁-C₆₀ alkylthio group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₇-C₆₀ alkyl aryl group, a substituted or unsubstituted C₇-C₆₀ aryl alkyl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a C₂-C₆₀alkyl heteroaryl group, a C₂-C₆₀ heteroaryl alkyl group, a substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q₁)(Q₂)(Q₃), —Ge(Q₁)(Q₂)(Q₃), —N(Q₄)(Q₅), —B(Q₆)(Q₇), —P(Q₈)(Q₉), or —P(═O)(Q₈)(Q₉), d2, d31, d32, and d4 are each independently an integer from 0 to 10, at least one substituent of the substituted C₅-C₃₀ carbocyclic group, the substituted C₁-C₃₀ heterocyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₁-C₆₀ alkylthio group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₇-C₆₀ alkyl aryl group, the substituted C₇-C₆₀ aryl alkyl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group, the substituted C₂-C₆₀ alkyl heteroaryl group, the substituted C₂-C₆₀ heteroaryl alkyl group, the substituted C₁-C₆₀ heteroaryloxy group, the substituted C₁-C₆₀ heteroarylthio group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group is: deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, or a C₁-C₆₀ alkylthio group; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀alkoxy group, or a C₁-C₆₀ alkylthio group, each substituted with at least one of deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q₁₁)(Q₁₂)(Q₁₃), —Ge(Q₁₁)(Q₁₂)(Q₁₃), —N(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), —P(Q₁₈)(Q₁₉), —P(═O)(Q₁₈)(Q₁₉), or a combination thereof; a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group; a C₃-C₁₀cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, or a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one of deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₁-C₆₀ alkylthio group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₇-C₆₀ alkyl aryl group, a C₇-C₆₀ aryl alkyl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a C₂-C₆₀ alkyl heteroaryl group, a C₂-C₆₀ heteroaryl alkyl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, —Si(Q₂₁)(Q₂₂)(Q₂₃), —Ge(Q₂₁)(Q₂₂)(Q₂₃), —N(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), —P(Q₂₈)(Q₂₉), —P(═O)(Q₂₈)(Q₂₉), or a combination thereof; or —Si(Q₃₁)(Q₃₂)(Q₃₃), —Ge(Q₃₁)(Q₃₂)(Q₃₃), —N(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), —P(Q₃₈)(Q₃₉), or —P(═O)(Q₃₈)(Q₃₉), and Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ are each independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₁-C₆₀ alkylthio group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₇-C₆₀ alkyl aryl group, a substituted or unsubstituted C₇-C₆₀ aryl alkyl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₂-C₆₀ alkyl heteroaryl group, a substituted or unsubstituted C₂-C₆₀ heteroaryl alkyl group, a substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, or a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group.
 2. The organometallic compound of claim 1, wherein M is iridium (Ir), platinum (Pt), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), thulium (Tm), rhodium (Rh), palladium (Pd), or gold (Au).
 3. The organometallic compound of claim 1, wherein X₁₁ is N, and X₁₂ is C(R₁₂); X₁₁ is C(R₁₁), and X₁₂ is N; or X₁₁ is N, and X₁₂ is N, and R₁₁ and R₁₂ are respectively as defined for R₁₁ and R₁₂ in claim
 1. 4. The organometallic compound of claim 1, wherein ring CY₂, ring CY₃₁, ring CY₃₂, and ring CY₄ are each independently a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a thiophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluoren-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluoren-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzotriazole, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group.
 5. The organometallic compound of claim 1, wherein at least one of Y₂ to Y₄ is N.
 6. The organometallic compound of claim 1, wherein Ria, R_(1b), R₂, R_(2a), R_(2b), R_(3a), R_(3b), R₄, R_(10a), R₁₁ to R₁₃, R₃₁, and R₃₂ are each independently: hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, or a C₁-C₂₀ alkylthio group; a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, or a C₁-C₆₀ alkylthio group, each substituted with at least one of deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, or a combination thereof; a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group; a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, a benzoisothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, or an imidazopyrimidinyl group, each substituted with at least one of deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a C₁-C₂₀ alkylthio group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a phenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, a benzoisothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, —Si(Q₃₁)(Q₃₂)(Q₃₃), or a combination thereof; or —Si(Q₁)(Q₂)(Q₃), —Ge(Q₁)(Q₂)(Q₃), —N(Q₄)(Q₅), —B(Q₆)(Q₇), —P(Q₈)(Q₉), or —P(═O)(Q₈)(Q₉), and Q₁ to Q₉ and Q₃₁ to Q₃₃ are each independently: —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, or —CD₂CDH₂; an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a phenyl group, or a naphthyl group; or an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a phenyl group, or a naphthyl group, each substituted with at least one of deuterium, a C₁-C₁₀alkyl group, a phenyl group, or a combination thereof.
 7. The organometallic compound of claim 1, wherein R_(1a), R_(1b), R₂, R_(2a), R_(2b), R_(3a), R_(3b), R₄, R_(10a), R₁₁ to R₁₃, R₃₁, and R₃₂ are each independently: hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, or a C₁-C₆₀ alkylthio group; a group represented by one of Formulae 9-1 to 9-61, 9-201 to 9-237, 10-1 to 10-129, or 10-201 to 10-355; a group represented by one of Formulae 9-1 to 9-61, 9-201 to 9-237, 10-1 to 10-129, or 10-201 to 10-350 in which at least one hydrogen is substituted with deuterium, —F, or a cyano group; or —Si(Q₁)(Q₂)(Q₃), —Ge(Q₁)(Q₂)(Q₃), or —N(Q₄)(Q₅), and Q₁ to Q₅ are respectively as defined for Q₁ to Q₅ in claim 1:

wherein, in Formulae 9-1 to 9-61, 9-201 to 9-237, 10-1 to 10-129, and 10-201 to 10-355, * indicates a binding site to a neighboring atom, “Ph” indicates a phenyl group, “TMS” indicates a trimethylsilyl group, and “TMG” indicates a trimethylgermyl group.
 8. The organometallic compound of claim 1, wherein a group represented by

in Formula 1 is a group represented by one of Formulae 2-1 to 2-3:

wherein, in Formulae 2-1 to 2-3, Y₂₁ to Y₂₃ are each independently C or N, Y₂₁ and Y₂ are linked to each other via a chemical bond, Y₂ and Y₂₂ are linked to each other via a chemical bond, Y₂ and Y₂₃ are linked to each other via a chemical bond, and Y₂₂ and Y₂₃ are linked to each other via a chemical bond, *′ indicates a binding site to T₁, *″ indicates a binding site to T₂, and * indicates a binding site to A₂ or M, and ring CY₂, Y₂, R₂, and d2 are respectively as defined for ring CY₂, Y₂, R₂, and d2 in claim
 1. 9. The organometallic compound of claim 1, wherein a group represented by

in Formula 1 is a group represented by one of Formulae CY2-1 to CY2-35:

wherein, in Formulae CY2-1 to CY2-35, Y₂ is C or N, R₂₁ to R₂₉ are each independently as described for R₂ in claim 1, and * indicates a binding site to M or A₂, *′ indicates a binding site to T₁, and *″ indicates a binding site to T₂.
 10. The organometallic compound of claim 1, wherein a group represented by

in Formula 1 is a group represented by one of Formulae CY3-1 to CY3-9:

wherein, in Formulae CY3-1 to CY3-9, Y₃ is C or N, R₃₁ to R₃₆ are each independently as described for R₃₁ in claim 1, and * indicates a binding site to M or A₃, *′ indicates a binding site to T₃, and *″ indicates a binding site to T₂.
 11. The organometallic compound of claim 1, wherein a group represented by

in Formula 1 is a group represented by one of Formulae CY4-1 to CY4-29:

wherein, in Formulae CY4-1 to CY4-29, Y₄ is C or N, Y₄₁ is N(R_(41a)), O, Se, C(R_(41a))(R_(41b)), or Si(R_(41a))(R_(41b)), and R₄₁ to R₅₀, R_(41a), and R_(41b) are each independently as described for R₄ in claim 1, * indicates a binding site to M or A₄, and *″ indicates a binding site to T₃.
 12. The organometallic compound of claim 1, wherein the organometallic compound is represented by one of Formulae 1-1 to 1-3:

wherein, in Formulae 1-1 to 1-3, M, ring CY₂, ring CY₃₁, ring CY₃₂, ring CY₄, Y₂ to Y₄, A₂ to A₄, T₁ to T₃, R₁₁ to R₁₃, R₂, R₃₁, R₃₂, R₄, d2, d31, d32, and d4 are respectively as define for M, ring CY₂, ring CY₃₁, ring CY₃₂, ring CY₄, Y₂ to Y₄, A₂ to A₄, T₁ to T₃, R₁₁ to R₁₃, R₂, R₃₁, R₃₂, R₄, d2, d31, d32, and d4 in claim
 1. 13. The organometallic compound of claim 1, wherein the organometallic compound is represented by one of Formulae 1-11 to 1-13:

wherein, in Formulae 1-11 to 1-13, X₃₁ is C(R₃₁) or N, X₃₂ is C(R₃₂) or N, X₃₃ is C(R₃₃) or N, X₃₄ is C(R₃₄) or N, X₃₅ is C(R₃₅) or N, and X₃₆ is C(R₃₆) or N, X₄₁ is C(R₄₁) or N, X₄₂ is C(R₄₂) or N, X₄₃ is C(R₄₃) or N, and X₄₄ is C(R₄₄) or N, R₃₁ to R₃₆ are each independently as described for R₃₁ in claim 1, R₄₁ to R₄₄ are each independently as described for R₄ in claim 1, and M, ring CY₂, Y₂ to Y₄, A₂ to A₄, T₁ to T₃, R₁₁ to R₁₃, R₂, and d2 are respectively as defined for M, ring CY₂, Y₂ to Y₄, A₂ to A₄, T₁ to T₃, R₁₁ to R₁₃, R₂, and d2 in claim
 1. 14. The organometallic compound of claim 1, wherein a highest occupied molecular orbital (HOMO) energy level of the organometallic compound is −5.25 electron Volts or less.
 15. The organometallic compound of claim 1, wherein at least one of T₁ and T₃ is a single bond.
 16. An organic light-emitting device, comprising: a first electrode; a second electrode; and an organic layer arranged between the first electrode and the second electrode, wherein the organic layer comprises an emission layer, and wherein the organic layer further comprises at least one of the organometallic compound of claim
 1. 17. The organic light-emitting device of claim 16, wherein the emission layer comprises the at least one of the organometallic compound.
 18. The organic light-emitting device of claim 17, wherein the emission layer emits light having a maximum emission wavelength of about 440 nanometer to about 470 nanometer.
 19. The organic light-emitting device of claim 16, wherein the first electrode is an anode, the second electrode is a cathode, the organic layer further comprises a hole transport region arranged between the first electrode and the emission layer, and an electron transport region arranged between the emission layer and the second electrode, the hole transport region comprises a hole injection layer, a hole transport layer, an electron blocking layer, a buffer layer, or a combination thereof, and the electron transport region comprises a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof.
 20. An electronic apparatus, comprising the organic light-emitting device of claim
 16. 